From time to time we come across the question why are the values of the Blocked URL requests at URL Filtering increasing on the dashboard, although the URL Filtering feature is disabled.

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In this post I would like to explain, what exactly we can see there.

The first value represents the number of the denied web requests in the last 24 hour.  This value equals the value of the Sites denied in last day (Forefront TMG Web Proxy) performance counter on a standalone TMG server. If you have an array the value shows the sum of the value of the Sites denied in last day (Forefront TMG Web Proxy) performance counters on the array members.

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The second value represents the number of incoming web requests in the last 24 hour.  This value equals the value of the Total number of request in last day (Forefront TMG Web Proxy) performance counter on a standalone TMG server. If you have an array the value shows the sum of the value of the Total number of request in last day (Forefront TMG Web Proxy) performance counters on the array members.

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The third value shows the rate of the values above as percentage.

The Total number of request in last day (Forefront TMG Web Proxy) counter will be incremented if a HTTP request hits the Web Proxy component.

Let’s have a closer look on what increases the Sites denied in last day (Forefront TMG Web Proxy) performance counter?

Well, there are different reasons behind this:

- Client authentication fails

- A rule does not allow accessing the web site

- User override scenario (http://technet.microsoft.com/en-us/library/ff685648.aspx)

- Error occurred on checking the URL categorization of the destination website

- At renegotiation of an SSL session, SSL certificate problem

- … etc.

As you can see the Sites denied in last day (Forefront TMG Web Proxy) counter covers more scenarios than just URL filtering.

Author:

Arpad Gulyas
Sr Support Enginner
Microsoft CSS Forefront Security Edge Team

Technical Reviewer:

Lars Bentzen
Sr. Escalation Engineer
Microsoft CSS Forefront Security Edge Team